Sperm production is at its peak during winter and early spring for most men, a new study has found.

However, gents with abnormal sperm production have the best luck in autumn, the findings out of Israel suggest.

Researchers from Ben-Gurion University looked at 6455 semen samples from men treated at an infertility clinic between 2006 and 2009. They found sperm production was much greater in winter, and began declining in early spring. Not only were counts up in colder months, but sperm swam much faster and had less abnormalities.

Autumn is typically a high point for the birth of new babies, Medical Daily reported. Studies on other animals have shown seasonal effects on fertility, but it was previously unclear whether human sperm improved during certain times of year.

According to the participant's samples - 2,690 had normal sperm production and 1,495 had sperm problems, like a low count. Anything over 15 million sperm per millilitre of semen is considered a normal count.

Men with normal sperm produced up to 70 million per millilitre during winter. Some also swam faster, making it easier for a woman to get pregnant. The following month it fell to about 68 million, only three per cent of which were speedy.

Changes in sperm could be related to temperature, the length of daylight exposure and hormone variation, according to Medical Daily.

The study was published in the American Journal of Obstetrics & Gynocology.